Merge pull request #229 from gostool/leetcode1791

Leetcode1791

leetcode/1791.Find-Center-of-Star-Graph/1791.Find Center of Star Graph.go

@@ -0,0 +1,8 @@
+package leetcode
+
+func findCenter(edges [][]int) int {
+	if edges[0][0] == edges[1][0] || edges[0][0] == edges[1][1] {
+		return edges[0][0]
+	}
+	return edges[0][1]
+}

leetcode/1791.Find-Center-of-Star-Graph/1791.Find Center of Star Graph_test.go

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+package leetcode
+
+import (
+	"fmt"
+	"testing"
+)
+
+type question1791 struct {
+	para1791
+	ans1791
+}
+
+// para 是参数
+type para1791 struct {
+	edges [][]int
+}
+
+// ans 是答案
+type ans1791 struct {
+	ans int
+}
+
+func Test_Problem1791(t *testing.T) {
+
+	qs := []question1791{
+
+		{
+			para1791{[][]int{{1, 2}, {2, 3}, {4, 2}}},
+			ans1791{2},
+		},
+
+		{
+			para1791{[][]int{{1, 2}, {5, 1}, {1, 3}, {1, 4}}},
+			ans1791{1},
+		},
+	}
+
+	fmt.Printf("------------------------Leetcode Problem 1791------------------------\n")
+
+	for _, q := range qs {
+		_, p := q.ans1791, q.para1791
+		fmt.Printf("【input】:%v      ", p.edges)
+		fmt.Printf("【output】:%v      \n", findCenter(p.edges))
+	}
+	fmt.Printf("\n\n\n")
+}

leetcode/1791.Find-Center-of-Star-Graph/README.md

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+# [1791.Find Center of Star Graph](https://leetcode-cn.com/problems/find-center-of-star-graph/)
+
+## 题目
+
+There is an undirected star graph consisting of n nodes labeled from 1 to n. A star graph is a graph where there is one center node and exactly n - 1 edges that connect the center node with every other node.
+
+You are given a 2D integer array edges where each edges[i] = [ui, vi] indicates that there is an edge between the nodes ui and vi. Return the center of the given star graph.
+
+**Example 1:**
+
+![https://assets.leetcode.com/uploads/2021/02/24/star_graph.png:w](https://assets.leetcode.com/uploads/2021/02/24/star_graph.png)
+
+    Input: edges = [[1,2],[2,3],[4,2]]
+    Output: 2
+    Explanation: As shown in the figure above, node 2 is connected to every other node, so 2 is the center.
+
+**Example 2:**
+
+    Input: edges = [[1,2],[5,1],[1,3],[1,4]]
+    Output: 1
+
+**Constraints:**
+
+- 3 <= n <= 100000
+- edges.length == n - 1
+- edges[i].length == 2
+- 1 <= ui, vi <= n
+- ui != vi
+- The given edges represent a valid star graph.
+
+## 题目大意
+
+有一个无向的 星型 图，由 n 个编号从 1 到 n 的节点组成。星型图有一个 中心 节点，并且恰有 n - 1 条边将中心节点与其他每个节点连接起来。
+
+给你一个二维整数数组 edges ，其中 edges[i] = [ui, vi] 表示在节点 ui 和 vi 之间存在一条边。请你找出并返回 edges 所表示星型图的中心节点。
+
+## 解题思路
+
+- 求出edges中前两个元素的共同值，即是中心节点
+
+## 代码
+
+```go
+package leetcode
+
+func findCenter(edges [][]int) int {
+	if edges[0][0] == edges[1][0] || edges[0][0] == edges[1][1] {
+		return edges[0][0]
+	}
+	return edges[0][1]
+}
+```